45 ACP Bullet Seating Determination

[RougeLeader]

Hello everyone! I've been working on some 45 ACP loads and ran into some failure to fire issues. It was an issue with the bullet seating depth, just a few thousandths off.

My question is if there is a better way to determine the proper seating depth for an arbitrary bullet for semiautomatic cartridges to prevent primer detonation failures than trial and error and educated guessing. Yes I do know that the 'proper' depth for this may conflict with cartridge feeding with some gun/projectile combinations. I'm just worried about the primer strikes in this case.

Just to take care of some other sort-of-on-topic replies, I do trim and prep my brass, I do know what seating depth is, I do know seating depth will be different for various projectiles, and I do currently have a working safe loading.
-RougeLeader

[Rifletom]

What weight bullet? What configuration[shape]? OAL? And, do you have dial calipers?
We have some unknowns here.

[dallasb]

Plunk test works well for me.

Sent from my SM-G950U using Tapatalk

[RougeLeader]

Rifletom,
My current loading is a 200gn LSWC. OAL is 1.260-1.261'' as tested between 20 rounds. I do have dial calipers, digital calipers, and a large micrometer.

[RougeLeader]

Dallasb,
What is a plunk test? I have not heard this term.

[gwpercle]

Seat the primers untill they bottom out in the primer pocket....no primers sitting high, that's bad.
Use your guns barrel and do the plunk test...when it passes the plunk test make sure it will fit into the magazine.
Make up some dummy rounds and you can see if they manually cycle from magazine into chamber and eject. If they do ...it's powder, primer and range time.
It isn't rocket science ...don't over think it.
Gary
Do a search on the term "plunk test" you will see. Basically you use your guns barrel as the chamber gauge . Chamber gauge's don't ensure a round will fit your guns chamber....so just use the barrel . When the round drops in (plunk)and drops out (plunk) that's doing the plunk test .

[RougeLeader]

gwpercle,
I do exactly as you said. I do make cycle-test dummy rounds, a least 2 mags worth actually for each load variation, and do seat my primers properly.
If by the plunk test you mean literally dropping them into the disassembled chamber and seeing if they are flush with the barrel hood then yes I do this as well. These are just standard SOP.

[pete2]

I don't understand what bullet seating depth could have anything to do with failure to fire if the round chambers.
A round that's too long will fail to chamber, this is why the plunk test. A high primer will fail to fire.

[Carmady]

I do trim and prep my brass

First off, I'm nothing close to a "serious" reloader, but I am lazy and proud of it.

One reason I load 45 ACP is because there's no need (according to my past research) to trim the brass. The 45 ACP headspaces on the case mouth, and those cases do not stretch as they can on other calibers. So I next to never check case length on them, unless something gets fishy.

If I were you, I'd give consideration to the possibility that your trimmed brass causes the cartridge to seat a tad low, and that would also carry the primer along with it, and that might be the cause of your failures to fire...light strikes due to increased distance from the firing pin to the primer.

[RougeLeader]

I have found that bullet design severely impacts bullet depth in regards to both failure to fire and failure to feed for my pistol. If I seat to 1.26'' with this bullet design then I get feed failures and severe leading. This leads to the conclusion that the OD of the LSWC is impacting and deforming against the end of the chamber. If I seat to 1.23'' then I get severe failure to fire issues, figure 1:12 rounds would be a failure.
I have tested this with remington and CCI primers, over 1000 rounds of ammunition between variations, and a constant powder load of bullseye.
Is it possible that my 1911 is just picky? Have you guys seen this sort of behavior?

[RougeLeader]

Rifletom,
I honestly hadn't considered the reduced length of trimmed brass and being and issue. I'll load non-trimmed once-fired for a few hundred loads and see what happens. You make a good point. A simple solution that for some stupid reason I didn't even think of.

[Jim Watson]

I have not seen bullet seating to affect primer ignition.
Do they fire if you cock the hammer and hit them again?
If so, that is a sign of a high primer. The first hitvseats it the rest of the way and the second fires it.

Does your gun have a titanium firing pin? Those can contribute to misfires.

[RougeLeader]

Jim,
I actually do have a titanium firing pin. I just had it installed as my previous pin had failed... come to think of it within a week or two of the time that these issues were encountered.
I was not aware that it would change the functionality of the weapon.

[Rifletom]

RougeLeader, the credit goes to Carmady regarding case length. You'll get this figured out, as it isn't difficult once you get rolling.

[74A95]

Seating depth of the bullet has nothing to do with your failure to fire. That's a completely different issue.

[cw308]

The plunk test is used with you barrel , with the barrel removed drop a loaded round in your chamber the bullet shouldn't extend past the barrel hood and will not stick in the chamber . You never have to trim 45acp cases . I use to until the people on this forum proved to me the cases never get to that length to trim . You can try the plunk test with just a case but it's for a loaded round test .

[reddog81]

If the round will chamber than OAL wil not effect primer ignition. If the round will not chamber the round will not fire I suppose...

What are the exact problems you are getting? Failure to go into battery, trigger problems, failure of the firing pin to ignite the primer? We need more detail otherwise everyone is just guessing.

[USSR]

Just to take care of some other sort-of-on-topic replies, I do trim and prep my brass...

What's to trim? I have yet to see a .45 ACP case that exceeds .898".

Don

[cw308]

reddog81
Correct on OAL , if the round won't chamber you slide wouldn't close . I use the Lyman chamber gage to test each round . Just another tool on the shelf.

[Nathan]

failure to fire issues

Do you mean the round does not fire when the hammer falls?

When you drop the hammer on a wooden pencil with eraser, what happens?

I do trim and prep my brass, ....

Really? To what length? Fired or sized?

[USSR]

RougeLeader,

Since you are using a SWC, put OAL out of your mind and concentrate on base to front band dimensions as shown below.



That being said, I will disagree with the dimensions shown above. Instead of the 0.940" length shown, I would suggest you stick the front band out 1/32" past the case mouth, giving you a length of 0.929". Hope that helps.

Don

P.S. - I also suggest a crimp of .469".

[Unclenick]

RougeLeader,

The titanium firing pin's lower mass means it slams into the primer with less inertia. This can fail to indent the primer fully. A titanium striker in a rifle can work because the mainspring accelerates it more rapidly than a steel one, allowing it to pick up more energy. But in the 1911 the hammer mass limits how much speed the strike can have and thereby, how much faster the lighter pin can go, and often it is not enough. I wound up abandoning one of these titanium pins myself. I bought it when they first came out, thinking to shorten lock time, but it turns out you have to go to a stiffer mainspring and a lighter hammer to have a chance at getting enough speed into it, and that messes with your trigger work. Just more trouble than its worth.

Seating long enough that the cartridge headspaces on the bullet and its head is flush with the barrel hood normally improves lead bullet accuracy and reduces leading by getting the bullet centered in the throat. If your leading is worsening with the bullet seated that way, I am a little suspicious of the barrel's throat geometry, but would need to look at it to know. A common target shooting gunsmithing practice was to apply a throating reamer to a 1911 barrel to make the taper of the leade more gradual and move it all slightly forward to make a tiny freebore for the LSWC bullet shoulders. It might be something to consider having done.

It occurs to me that if you headspace on the bullet AND you have a titanium firing pin, the pin pushing the bullet into the throat could cost it some of its energy. I've not had the problem with a steel pin and that seating method (third from left, below), but I always use Federal 150 or 150M primers, known for the sensitivity and commonly recommended for people having trouble getting the weakened strikes from a tuned revolver to fire consistently. So you might experiment with that change.

Another factor is that proper primer seating takes more force than many suspect, so you could also be failing to properly set the bridge thickness (the thickness of priming mix between the tip of the anvil and the inside bottom of the primer cup). The primer should be seated to reconsolidate the primer assembly (push the cup and anvil closer together against priming mix and foil) about 0.003" deeper than the point at which the anvil feet first touch the floor of the primer pocket.